Dana 20 leaking

Discussion in 'General IH Tech' started by DrMaserati, Apr 28, 2004.

  1. DrMaserati

    DrMaserati High Wheeler

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    Any leak experts out there? I just serviced the Dana 20 t/c in the Scout. Everything is pristine inside, and I let it drain completely overnight while I cleaned and painted the bottom cover. When I refilled it I changed from standard gear oil to sythetic 20-50. I knew that could potentially cause some leaks to show up, but I was hoping for the best.

    It is now leaking. But not until it has sat for about 10 minutes. When I park it, there is no leak initially, then about 5-10 minutes later it starts dripping. Then after leaking out a tablespoon or two it stops. I know it's not coming from the bottom cover, but that's about all I know. It's now dark outside and I won't be checking it until daylight tomorrow. Any suggestions on what is the most likely source of the leak? Where should I start looking?
     
  2. Foy

    Foy High Wheeler

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    Jim-
    I've never had a D20 opened up and can't guess at the source of your leak, but is it possible that the seal or cover plate tolerances just aren't up to lubricant as light as 20W? Again, I'm not well versed in the viscosity nomenclature, but I've read here that straight 50 weight motor oil has essentially the same viscosity properties as GL1 mineral oil wihch is the OEM spec fluid for the D20. I'm just curious if there is a compelling reason to run 20W50 and if the 20W might be your problem. Seems easy enough to find out--complete drain and refill with 50W, and see what happens.


    Foy
     
  3. George Womack

    George Womack High Wheeler

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    One possibility is that oil is leaking past the splines of the front or rear output shaft. The output shaft seals seal the outside of the yokes, but not the inside. The fix is to put a little RTV silicone on the output shaft splines before installing the yokes.

    Another common leak is at the shims of the front output shaft rear bearing retainer. Again, coating the shims and retainer plate with RTV will prevent a leak here.
     
  4. Dennis Bernth

    Dennis Bernth Moderator Staff Member Moderator

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    I vote for George's diagnosis. I've had other make and model transfer cases leak at the splines. They normally came with some type of rubber 'washer' to seal that area, but after all this time the rubber usually isn't the most pliable anymore. It's possible that the level of gear lube in the case before you serviced it wasn't high enough to leak, plus with it being syn and thinner it would find it's way out easier.
     
  5. DrMaserati

    DrMaserati High Wheeler

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    I think those may both be significant factors. Once I locate the leak, I think I will just leave things alone to see if it quits leaking as the level drops. Once I've determined how low the level has to be to stop leaking, then I'll make whatever repair is needed. One place I'm considering in addition to those mentioned is the trans to T/C gasket. At this point it appears to be coming from somewhere on the front of the T/C.
     
  6. DrMaserati

    DrMaserati High Wheeler

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    Well, the verdict is in. It turned out to be the transmission to T/C joint. It was loose, and one of the upper bolts had backed out a full quarter inch. I tightened them and torqued to 30 ft-lb. I couldn't find a torque spec for the Dana 20, so I used the spec for an 18. If someone has a corrected torque spec for a Dana 20 to 727, please let me know.

    I apparently lucked out with the gasket. It hasn't leaked a drop since I tightened things up. Thanks for the suggestions, and I'm going to keep an eye on the splines on the output shafts.
     

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